System for mounting the outer hair spring end of a watch movement

ABSTRACT

In a watch: A balance-and-hair spring time keeping oscillator, the balance being journalled in bearings and the inner hair spring end being mounted on the balance shaft while its outer end is fastened to the watch frame by clamping between a frame part and the free end of a leaf spring biased against said frame part, the outer hair spring end being deformed during the first assembly to assume the step-like shape of said frame part in order to reproduce the position after repair and reassembling.

United States Patent 11 1 1111 3,872,663 Meitinger 1 1 Mar. 25, 1975 15 SYSTEM FOR MOUNTING THE OUTER 1,037,741 9/1912 Dudley 511/115 x HAIR SPRING END OF A WATCH 3,350,875 11/1965 Siefert et a1. 58/115 X MOVEMENT Inventor: Heinz Meitinger, Mutlangen,

Germany Bifora-Uhren J. Bidlingmaier GmbH, Schwabisch Gmund, Germany Filed: Jan. 2, 1974 Appl. No.: 429,580

Assignee:

Foreign Application Priority Data Jan. 11, 1973 Germany 2301147 References Cited UNITED STATES PATENTS 12/1908 Ball et a1 58/115 Primary Examiner-Edith Simmons Jackmon Attorney, Agent, or Firm-Parmelee, Miller, Welsh & Kratz [57] ABSTRACT In a watch: A balance-and-hair spring time keeping oscillator, the balance being journalled in bearings and the inner hair spring end being mounted on the balance shaft while its outer end is fastened to the watch frame by clamping between a frame part and the free end of a leaf spring biased against said frame part, the outer hair spring end being deformed during the first assembly to assume the step-like shape of said frame part in order to reproduce the position after repair and reassembling.

2 Claims, 2 Drawing Figures PATENTEB HARZ 5 i975 snznanrg all BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a system for mounting the outer hair spring end at a frame part of a watch movement.

2. Prior Art There are several systems known to mount the outer hair spring end in watch movements.

In the first of the most common systems, the outer hair spring end is clamped by means of a conical pin in a bore of a member which in turn is connected with a frame. In the other known system, the outer hair spring end is urged against a projection fastened at the frame by means of a screw and a flat element so to fix the hair spring end. Both systems have the drawback that there is quite a number of individual parts which, in particular, for watches must necessarily be very small, thus, causing difficulties during assembly and rendering the manufacture thereof expensive.

In addition, there are a number of means for mounting the outer hair spring end by means of glue or welding or otherwise. When using glue the assembling is delayed due to the setting time necessary for the glue In case of thermoplastic glue the mounting position must be heated which is relatively difficult because the hair spring itself must not be heated in its effective portions, and the same restriction is applicable to other components of the watch movement.

SUMMARY OF THE INVENTION It is the object of the present invention to eliminate the drawbacks mentioned above in order to reduce the expense of manufacture in general.

A further object of the invention is to provide a mounting system for the outer hair spring end of watches such that after disassembly of the movement and repair the outer hair spring end will be accurately positioned as before when reassembling the watch again.

The invention provides a clamping spring fastened with one of its ends at the frame while its other distal free end is biased against a part of the frame, the hair spring end being clamped between said part and the biased clamping spring end. Thus, there are no parts to be assembled or disassembled or to be screwed, the danger being eliminated when such a screw connection inadvertently becomes loose. The system moreover provides the desired advantage of inexpensive mass production because in the preferred embodiment, the clamping spring is mounted at the frame preferably at a bridge which carries a balance shaft bearing in such a manner that the connection cannot be disassembled any more. The part of the frame at which the hair spring end is clamped will preferably be a projection of said bridge which may be bent to extend perpendicularly with respect to the plane thereof. Such a system may be implemented with a minimum of expense. If the part of the frame is provided with a step and the distal end of the clamping spring with a hook shaped complementary with respect to said step the outer hair spring end when assembled initially will be deformed to assume the shape of a step and thus is mounted in position not only under the action of the clamping spring bias but also due to the shaping of the three members which form the connection. This desired position of the hair spring end will be reproduced when reassembling a disassembled watch movement. This reproducible positioning will be the easier if the part is provided at a readily accessible position where it is not covered by other members of the movement frame.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will be described in detail hereunder, reference being made to the accompanying drawings, wherein:

FIG. 1 illustrates those parts of a watch movement which relate to the invention, in a top plan view; and

FIG. 2 is a side elevation looking in the direction of arrow A of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT At the upper bridge of the movement which in this case is the balance bridge 2 the bearing 5 ofthe balance shaft 10 is mounted. The regulator arm 3 is in conventional manner rotatably mounted on bearing 5 and provides the opportunity to vary the effective length of hair spring 1 and thus the oscillation frequency of the balance. This is due to the closed slot at projection 6 in which the outermost winding of hair spring 1 is received.

The system according to the invention comprises the projection 9 bent perpendicularly with respect to bridge 2 and clamping spring 7 rigidly mounted at nose 8 of bridge 2. The outer end of the hair spring to be mounted is positioned between the end 4 of spring 7 and projection 9 and is clamped due to the bias to which the spring 7 is subjected with respect to projection 9 due to its position. In order to provide a reproducible positioning of the hair spring end a step 12 is provided at projection 9. The end 4 of clamping spring 7 is shaped like a hook 13 whose configuration corresponds complementarily to that of step 12.

When positioning the hairspring 1 it is deformed due to this configuration to assume the shape of the step so that the mounting elements and the hair spring all have similar shape and a shifting of the outermost hair spring winding in the direction of the balance shaft is eliminated.

The system according to the invention provides the possibility to connect the outer hair spring end in a simple and inexpensive manner with the watch movement frame. In order to disassemble the connection, it is just necessary to remove the clamping spring end 4 from projection 9 by exerting a small pressure counteracting the bias. The reassembly occurs in the same manner in inverse order, the step of the hair spring end at any time centering between the hook 13 and step 12 of projection 9. Since the leaf spring 7 is rigidly fastened to the frame the system according to the invention does not require any thread. This permits the manufacture of bridge 2 in an inexpensive manner from thin bendable material. Moreover the risk of screws becoming loose is eliminated. Finally, the assembly itself is facilitated because there are no parts at all which are not rigidly connected with others.

What I claim is:

1. In a time keeping instrument movement: A frehook and said step.

2. A system for mounting the outer end of the hair spring of a watch balance comprising a first fixed memher of the watch frame and a second resilient member having a first end rigidly fastened at said frame and having a second distal end resiliently urged against said first member, said first member having an indentation extending perpendicularly to said hair spring end in the plane of the latter, said second member distal end having a shape complementary to that of the first member in the area of contact between them, and the hair spring end being positioned, during assembly of the watch, between said first member and the distal end of said second member so to make it assume the shape of said indentation. 

1. In a time keeping instrument movement: A frequency standard comprising a balance driven in oscillation about a balance shaft and a hair spring having one end connected to said shaft and the other end connected to a part of the movement frame, a clamping spring being fastened with one of its ends at said frame while its other end is biased against said frame part, said other hair spring end being clamped between said biased clamping spring end and said frame part wherein said frame part has a step shaped configuration and said biased clamping spring part has a hook shaped configuration complementary with respect to said step so as to deform the said clamped hair spring end when the same is positioned for the first time between said hook and said step.
 2. A system for mounting the outer end of the hAir spring of a watch balance comprising a first fixed member of the watch frame and a second resilient member having a first end rigidly fastened at said frame and having a second distal end resiliently urged against said first member, said first member having an indentation extending perpendicularly to said hair spring end in the plane of the latter, said second member distal end having a shape complementary to that of the first member in the area of contact between them, and the hair spring end being positioned, during assembly of the watch, between said first member and the distal end of said second member so to make it assume the shape of said indentation. 